Friday, April 28, 2017

Brian
Humphrey from England, a well-known plantsman/nurseryman – and
seldom is one man both – is writing a book on propagation. He asked
me to look at the maple grafting part in case I “see any mistakes
which should be corrected.” The twenty pages I reviewed couldn’t
have “mistakes” because it was merely discussing various methods
and observations about maple propagation – and there really isn’t
a right or wrong way. I did learn a few things and got some ideas to
try at my nursery, and it wasn’t the first time that Brian has
shared his plant knowledge with me.

The
following is my response to some of the topics that he brings up, but
I won’t take the liberty to reveal his part – you’ll have to
buy the book yourself.

Acer x 'Purple Haze'

You
mention the “remarkable” hybrid A. x ‘Purple Haze’. It arose
in an outdoor seed bed of Acer griseum, and was noted for larger
leaves with purple undersides. I sent plants to Europe 12-15 years
ago, to Cor Van Gelderen and maybe others, and I was trying to
receive confirmation that it really was a hybrid. I was hoping that
“science” would look at it and make an official determination. I
heard nothing further until the Maple Society Convention in Belgium
in 2011. Generally half the attendees at these events are botanists,
and the other half are simple rustics such as myself. I have
witnessed that most of the academics defer to Piet de Jong, that he
is considered the highest authority on Acer. He smugly claimed that
that the hybrid was “impossible,” that ‘Purple Haze’ was
simply a variation within A. pseudoplatanus. Interestingly the
griseum-appearing leaf colors a fantastic orange-red in autumn, and
I’ve never seen an A. pseudoplatanus do that.

Acer x 'Sugarflake'

Acer x 'Cinnamon Flake'

More
ornamentally worthy than ‘Purple Haze’ is Acer x ‘Sugarflake’
and if it’s a hybrid (saccharum x griseum) then it is another cross
between different sections. De Jong also dismissed that as a hybrid,
and was certain that it was just a variation of Sugar maple. Of
course he has never seen a ‘Sugarflake’ specimen, and I wonder
what he would make of the (somewhat) exfoliating trunk which reminds
me of x ‘Cinnamon Flake’ (griseum x maximowiczianum).

Thirty
years ago seedling availability of Acer griseum was rare, so I
propagated the paperbark onto Acer rubrum. One of the original grafts
still grows in front of the house of the late Dr. Corbin of Portland,
Oregon. The union is still smooth and the top and bottom were the
same size the last time I saw it, but of course of very different
color. Occasionally a rubrum sucker will try to form, and the family
has been instructed to rub them off when small.

Acer griseum 'Narrow Form'

I
once had a seedling of A. griseum that was notably narrow, and I
thought that if we propagated it would make a perfect street tree.
When my specimen was about 15’ tall, a customer – and now I can’t
even remember who it was – begged and begged to buy it. I didn’t
want to sell it but eventually I relented. Before shipping I
harvested a few apical scions and grafted them on the only rootstock
I had – Acer rubrum. A few grafts took and all of them have
proceeded to grow as regular griseums, and none of them exhibit the
narrow form. If you look at Buchholz introductions on our website
you’ll notice Acer griseum ‘Narrow Form’. I don’t propagate
it at all anymore because its not at all narrow.

Acer nipponicum

I
have grown a few Acer nipponicum, but always as seedlings. I once
asked Peter Gregory if he knows of a suitable rootstock and he
suggested that I try Acer pseudoplatanus “because it accepts almost
everything.” My grafting resulted in 100%... failure, and I have
never wasted my time again.

Acer pentaphyllum

I
notice that the suggested rootstock in Cor Van Gelderen’s table for
Acer pentaphyllum is Acer pseudoplatanus. I have never tried that
because I achieve good success with Acer rubrum.

Acer buergerianum 'Angyo Weeping'

Acer campestre 'Carnival'

Acer circinatum 'Baby Buttons'

Acer shirasawanum 'Moonrise'

In
the section on Summer Grafting – “Some recommend that for species
other than A. palmatum summer grafting should be delayed until
September.” I don’t know why to wait if the wood looks ready.
Last August we had success with Acer buergerianum, campestre,
circinatum, conspicuum, japonicum, macrophyllum, palmatum,
pentaphyllum, pictum, shirasawanum and sieboldianum. Admittedly the x
conspicuum ‘Phoenix’ grafts were only about 50%. It was our best
year ever and my propagator will be getting a raise. Of course I know
that next year could be our worst ever, and I’m sure no one will
want to return the extra money. The point is that you can
have good success with various species without “waiting until
September.”

My
success rates with grafting in October is that the earlier the
better. I think I it is probably weather related, with some Oregon
Octobers being cold and gloomy and others being warm and sunny. We
really like to finish by mid-September. I was surprised to see
Vergeldt in Holland grafting on October 20 one year. He used low
plastic tubes with bottom heat and kept the grafts dripping with
sweat. The rootstocks were pruned harshly with no foliage remaining,
so there was no chance of them catching mildew or other disease.
After 20 days, the grafts were uncovered and Vergeldt’s son implied
that they would have good success, of course depending somewhat on
the cultivar used. Two days later I flew home and copied the Dutch
method as best as I could, but my results were poor. I couldn’t
duplicate the feel of a Dutchman’s greenhouse – my humidity and
light are so different in Oregon.

Saya deleafing scions

I
prefer to deleaf all scions – it just keeps the operation cleaner.
I have experimented with keeping leaves on and that works as well,
but it puts me in a bad mood to walk past a withered moldy mess.
Besides I have grown closer to my youngest (now 11) daughter when we
deleaf scions in the evening after dinner. She is fast!

Acer palmatum 'Japanese Princess'

Acer palmatum 'Ikandi'

We
had some empty spaces on our hot pipe after grafting Fagus, Quercus,
and other species. We had about 200 rootstocks from failed summer
grafts and on Feb. 20 I cut scions of Acer palmatum ‘Japanese
Princess’ ‘Ikandi’ ‘Alpine Sunrise’ and the new ‘Bloody
Talons’. All scions came from stock in the greenhouse and on Feb.
20 they were just beginning to swell. They were kept on the hot pipe
for 20 days and now, two months later, we see that nearly everything
is vigorously growing. I have had the opposite results before too. We
keep our rootstocks in their pots and do no “drying off.” We
don’t dry off our summer rootstocks either. What I don’t like
about the hot pipe – we call callus tube – is that we must graft
about 3” above on the trunk so that the union is at the heat
source, when I would much prefer to have my grafts as close to the
soil as possible.

I
have “stick-budded” before, but I don’t like it because the
scion-rootstock size disparity means that I have to keep the plant
for an extra year or two before the cultivar catches up, so they are
not suitable to sell as one-year grafts. Years ago a Chinese woman
competitor propagated all of her maples via stick bud. Her product
looked wimpy and vulnerable compared to a normal side graft and I
took a lot of her business away.

On
the other hand my sister lived in the woods near the Oregon coast,
and Acer circinatum grew wild just past her lawn. For fun I stick
budded a couple dozen red laceleafs on her vines and some actually
took. They were never very vigorous because she didn’t top the
circinatum rootstock; nevertheless it was an odd sight to see red in
her green jungle.

Acer circinatum 'Little Gem'

Juniperus squamata 'Blue Star'

I
was surprised to see the mention of A. circinatum ‘Little Gem’ as
a candidate for top grafting. If palmatum rootstock is used the vine
cultivar – whether a witch’s broom or an upright grower – will
outgrow the rootstock and the product will always need the support of
a strong stake. I find this also true with palmatum cultivars that
originate from brooms such as ‘Shaina’ or ‘Kandy Kitchen’.
Other dwarves or spreader palmatum cultivars such as ‘Little
Princess’ or ‘Japanese Princess’ seem to be ok top worked,
although stem colors seldom match. Whether with conifers or maples,
as well as with other plants, what happens to the rootstock of a top
graft can vary greatly. Some stay skinny forever and some expand
significantly. If you graft a Juniperus squamata ‘Blue Star’
(witch’s-broom origin) atop a J. scopulorum ‘Skyrocket’ the
‘Blue Star’ seems to act as a bottle stopper and the stem fattens
up nicely. Abies koreana ‘Ice Breaker’ works but Abies koreana
‘Blauer Eskimo’ does not. I suppose the species of rootstock in
question is a factor too.

Years
ago the propagator at Monrovia Nursey wanted to visit because he had
heard that Buchholz did well with maples. I didn’t keep anything
secret from this southern California university graduate of
horticultural science. A week later I requested a visit to their
propagation department and after a lot of hemming and hawing from the
Higher Ups, I was finally granted permission. Boy, did we do things
differently! Their rootstocks were about 2/16-3/16” caliper growing
in 2” by 2.5” deep “rose pots.” I wondered how often they
would need water on a hot day. Their crew performed side veneer
grafts with leaves still on the rootstocks, so the scions started out
in a good deal of shade. The propagator admitted that they had to
frequently reduce the top foliage which was a very labor-intensive
task. By contrast we use 3 9/16” pots with a rootstock caliper of
about ¼”. Our container’s volume is about 8 times larger that
Monrovia’s and of course they take up more room in the greenhouse
but at least we don’t have to constantly prune.

Monrovia
had already finished a few thousand grafts, and I was shocked to see
their full-time watering man with a small wand and with very low
water pressure going up and down the pots. Each pot would be covered
at least ten times before it was sufficiently wet, and great care was
taken that no
water ever touched the grafted union. They kept up this practice for
about two months before the grafts were deemed safe for overhead
water. What a boring job their hand-watering must have been, and I
think that the irrigator was a university graduate too.

At
Buchholz Nursey we care less about the ingress of water into the
graft, and sometimes our overhead is turned on one day after the
graft was made. However we use large 8 x 3/8 x 0.20 budding stripes
and begin wrapping ¼” above the graft union and end ¼” below.
We leave no gaps in the budding strip, nor do we seal the top. This
method works for maples and conifers, and because it does we’ve
never experimented with any other way, although I am aware that many
nurseries in Europe and America secure their grafts differently.

Total removal of rootstock in April

We
head back the rootstock on our summer grafts at least once, and
perhaps twice for those grafted earliest. In the spring, (about the
first of April in the greenhouse) when the scions show a couple of
inches of new growth the rootstock is completely removed, leaving one
bud set on the rootstock above the graft.

Considering
using 2-year scionwood – and larger scions – it is not a practice
at Buchholz Nursey unless the 2-year wood is the only type available
and large enough. But I have seen obscenely large 2 or 3-year scions
used in England (Peter Catt) with apparent success. I understand one
of the goals of horticulture is to “improve” on nature and to
speed her up so that we can sell the product more quickly. I probably
will experiment this summer with larger scions, but I wonder if my
graft percentage will go down.

I
know that Vertrees recommended drying off rootstocks (1978) at least
with A. palmatum. My first years I did as told, but eventually I
stopped because I couldn’t see the value in it, and actually there
seemed some danger in the endeavor to adequately rewet the pots.
Always keep in mind that the solo propagator has the freedom to
experiment and follow his inclinations; those with employees
inevitably compromise and often adopt practices where the employees
will do the least amount of harm.

We
overwinter summer grafts in frost-free greenhouses, but some
experimenting on temperature lows might be interesting. 15 years ago
we had 18,000 laceleaf and ‘Bloodgood’ grafts in a greenhouse
that collapsed under heavy snow. It was a custom-graft project where
the customer owned all the rootstocks and provided all of the scions.
Throughout the night the grafts were exposed to 3-5 degrees of frost,
then early in the morning the plants were transferred to an
above-freezing greenhouse. We threw out 168 plants that were broken
at the graft, but everything else looked ok. That spring we were
pleased with our normal 90-something percent success rate, and I was
glad that I never bothered the customer (Ekstrom Nursery) about the
incident.

1 gallon Buchholz maple

Competing
nurseries usually pot up their one-year grafts into 1-gallon pots one
year after grafting. They are watered and fertilized heavily and kept
in warm poly houses. They are staked onto bamboo where some whips
achieve 3’ of growth. The following spring they are shipped to
garden centers as a plant slightly less than two years old. At
Buchholz Nursery we don’t stake *Acer palmatum cultivars – we
prune instead – and keep them an extra year. Our 1-gallon pots are
more husky with greater caliper. These days the competition charges
between $10-12 for their one gallon pots; we charge between $14-16
for ours. Admittedly their system is more profitable, but I am more
proud of my plants. Furthermore, when growing the gallons on to
larger sizes, our future plants will have more impressive shapes than
the pushed-whip method.

Acer palmatum 'Ryu sei'

*An
exception would be A. p. ‘Ryu sei’ where we want height first.
When they are as tall as we want, then they are topped to form a
well-branched umbrella shape.

One
of the best aspects of horticulture is that you can rub shoulders
with some of the greatest plantspeople and learn from their
experience. There have also been times when dumbshits teach me a
thing or two. I don’t know where I fall that continuum, but at
least I’ve been able to make a living.

Friday, April 21, 2017

The last two weeks
of April, and the first into May, are by far the most stressful for
this nurseryman. The reason is that I fret about frost. We are so
exposed, with orders sitting out waiting to ship, and I look at the
weather forecast, sometimes more than once per day. Tonight, for
example, the low is projected at 34 F (1.1111111 degree C), with “a
passing shower or two.” Earlier this “spring,” 34 F was
predicted and we got to 31. Fortunately, at that time there was less
new growth, especially on maples, but it did smudge the blossoms on
Rhododendron 'Seta' and 'Pink Snowflakes'.

Bleached leaves of Acer palmatum 'Scolopendrifolium'

Watching the forecast

In the early 1980's
we plummeted to -26 F on May 5th, and though the maples'
new growth was reduced to mush, the nursery was fairly new and not so
much was lost. Another May 5th we exceeded 100 degrees and
some maple cultivars, such as A.p. 'Scolopendrifolium' had every cell
of chlorophyll bleached out. For my money, I'll take excessive spring
heat over numbing frosts. Nature hands to us each of our days, and
she has shown me in my career many weather records, all of which cost
me money. The extremes delight the pretty weather lady on TV, and she
is comfortably paid whatever the temperature. Perhaps I should cuddle
up with her and she can caress the worry from my brow.

Acer mandshuricum

Acer triflorum

Acer triflorum

Roy Lancaster

The first maples to
leaf out in the garden are a couple of tri-lobed species, Acer
mandshuricum and Acer triflorum, and both come from the same brutally
cold areas in northeastern Asia. It seems odd that they are the first
to leaf out, and one would suppose that the opposite would be true.
By studying leaves alone you might be hard pressed to tell the
species apart, and for me the main identifying feature of triflorum
is the birch-like exfoliating gray bark, whereas mandshuricum has a
dark-brown and rough bark without much exfoliation. Since these
species leaf out the first, they decide to also color in the fall the
first, around mid-September in my Oregon garden. Acer mandshuricum
was first described by the botanist Maximowicz in 1867, and a
specimen was already in Kew Gardens in 1904. Surprisingly the Acer
triflorum was a later introduction and didn't reach Europe until
1923. Both species can be found in arboreta and snob gardens, but
seldom does the typical home gardener plant one; indeed we only sell
a small handful each year. Various plantsmen display a curious
tendency to champion their favorite trees, and maybe these
Johnny-maple-seeds – like Roy Lancaster of England, actually
accomplish some good, but I am a rather jaded entrepreneur and at
this point I don't really care who grows what.

Acer griseum

Davidia involucrata

I feel compelled to
mention another maple in the trifoliata section, Acer griseum,
which takes a little more time to leaf out and so I worry about it
less for spring frosts. It is native to central China at altitudes
between 5,000 to 6,500' and was introduced to cultivation by E.H.
Wilson in 1901 while he toiled for the Veitch Nursery firm in
England. Wilsons' primary objective on his Chinese plant-hunting
venture – as demanded by old-man Veitch – was to find and acquire
seed of Davidia involucrata, and to “not waste his time on anything
else.” But it turned out that the griseum – the “Paperbark
maple” – was to become far more popular ornamentally. Take my
hometown of Forest Grove, Oregon, for example, a sleepy berg of
20,000 souls. You will find griseum used as a street tree, but I've
never even seen one “Dove tree,” Davidia involucrata. 37 years
ago, when I started my nursery, that wasn't the case, and the A.
griseum was also quite rare. In the ensuing years, urban forestry
planners and homeowners discovered how tough and beautiful was the
griseum species, and that was accompanied by the success of
nurseryman, especially in Oregon, to germinate and produce the
species by the many thousands… when previously they were considered
difficult. Consequently the “value” of griseum has declined –
quite substantially – where I could sell a 5”caliper tree for
about $350.00 twenty five years ago, and today it will only be about
$170-190.00.

Acer japonicum 'Giant Moon'

Outside the Acer
japonicums don't leaf out any sooner than the palmatums, but inside
the greenhouses they sure do. 'Giant Moon' is in full fat leaf and
already the 3-gallons are crowding each other. They have husky trunks
and will need potting up soon. I have to remind the crew that they'll
need additional water – the plants that is – and even though some
have worked here a decade or more, the transition from winter to
spring irrigation remains a novel concept. The disconnect with the
needs of the plants irks me, like we're making no progress, but
attentive plants people are in low supply and most with skill already
own their own nursery. I can stand at the end of a 100' greenhouse
and tell you what needs water on any given day of the year. If the
tree doesn't prosper then neither do I, and as you can tell: I fret
about more than just frosts.

GH18 Maple grafts

Juana grafting

This time of year I
love to wander into GH 18, our maple liner house. Our ace propagator,
Juana, beams with pride when I tell her once again she did an
excellent job. We grafted about 24,000 Acer last summer. A few will
put on some new growth if done early but most sticks remain tight
throughout the fall and all winter. It's actually a worrisome sight
in winter with a multitude of things that can go wrong, such as
heater failure, wind storms, record snow, wars, acts of god etc. So,
when you finally see a high success percentage of gaily arrayed scion
colors it is a joy to visit them daily.

Acer palmatum 'SnowKitten'

Juana asked me last
September when would we graft Acer palmatum 'SnowKitten' – the new
variegated mutation from 'Mikawa yatsubusa'. I cut all of the scions
and apparently she was getting anxious, and I already know that she
would like to take one home once we have a chance to build up our
stock. 'SnowKitten' is a terrible name for a maple but that's what we
are stuck with, and I too had observed our possible scion source for
the previous two months. A two-gallon pot, my original start, and
eight little one-gallon propagules from the original was all that we
had for scionwood, and none of it looked very good. I determined that
it wasn't worth the effort and we'd just skip a year. Juana
disagreed, and she looked me straight in the eye in challenge, a
situation I actually liked. So, I told her to go ahead and cut the
scions and graft as many as she could. I must impress upon the reader
that she had absolutely nothing to work on with, and yet I
just went and counted 31 cute healthy plants. If anyone is in need
for some extra loaves and fishes, Juana can probably pull it off.

Acer palmatum 'Fairy Hair'

Also quite
impressive was our “take” on Acer palmatum 'Fairy Hair', where
not only did we achieve a fantastic 99% (seemingly) success rate, but
the scions have bolted with unusual vigor. 'Fairy Hair' used to be
named 'Fairyhair' – one word – and since it was my introduction I
can spell it anyway I want. But when it was listed in the
Vertrees/Gregory Japanese Maples book, liberty was taken to
alter the spelling. I shrugged and went along with the change since
Timber Press would probably not issue a recall to correct the
mistake. At one point we had endless scion wood for 'Fairy Hair' so I
began to cash out on the stock plants. They easily sold and I guess I
got carried away, for the following season I was hard pressed to find
good scions. That was about five years ago but now we're back to a
good supply. One hundred plants in GH 11 in 7 gallon pots had a
wonderful growing year and they shot multiple shoots between 18-24”
long. These were cut into about three scions each with the soft tips
thrown away. Juana did her magic and now we have a crop growing like
weeds.

Acer palmatum 'Fairy Hair'

The largest 'Fairy
Hair' in the world is planted (in full sun) along the main road into
the nursery. A frost probably wouldn't harm it as the leaves have not
yet fully emerged. Planted next to it is probably the largest Acer
palmatum 'Mikawa yatsubusa' in the world, and it is very much
in leaf. In the past we would cover it with plastic when lows were
predicted, but that was such an effort for its large size that now we
do nothing. I know that a hard frost would render it unsightly for a
few months, but by July it would push out new growth and look fresh
again. Of course, I would require a three-month vacation from the
nursery during Mikawa's recovery.

Acer shirasawanum 'Autumn Moon'

Acer shirasawanum 'Moonrise'

The Acer
shirasawanums are generally the last of the “Japanese maples” to
leaf out as evidenced by our original – and now too large for its
place – 'Autumn Moon' planted by the office. I was given this tree
in a one-gallon pot years ago by a sweet woman who has long since
passed. What was her name – Marjorie? Anyway, she was the sister of
Del Loucks, he who has introduced many cultivars into the trade. His
sister also had her foot in the Vertrees door and so she was one of
the first to acquire 'Autumn Moon'. It was raised by Vertrees as a
seedling from Acer shirasawanum 'Aureum' and selected in 1978.
Thousands of 'Autumn Moon' have been produced over the years and I
have been responsible for many of them. Another seedling selection
from 'Aureum' was discovered and named 'Moonrise' by Carl Munn of
Oregon, but surprisingly it was never mentioned in the latest (4th
edition, 2009) Japanese Maples. Many growers prefer 'Moonrise'
as it perhaps withstands full sun better than 'Autumn Moon'.

Metasequoia glyptostroboides 'Kools Gold'

One can always worry
about other plants freezing besides Japanese maples. A crop of
Metasequoia glyptostroboides 'Kools Gold' was photographed in
mid-April a few years ago. Some had already been shipped but some
still remained at the nursery. They were hit with 29 degrees F one
night and a day later all I could do was groan. Every plant's new
growth reacts differently to frost, and the dazzling delicacy of
'Kools Gold' didn't fare so well. We potted them up and hid them in
the back somewhere and by July they looked great again.

Picea glauca 'Daisy's White'

Picea glauca 'Pixie Dust'

Picea glauca 'Alberta Blue'

The “Alberta
spruces,” Picea glauca var. albertiana 'Conica' display about a
quarter inch of vulnerable new growth at this time. Keep in mind that
not all cultivars of Picea glauca – the “White spruce” – are
dwarf compact pyramids designated as var. albertiana, and
'McConnal's Gold' would be an example of a regular sized upright
tree, except one that features cream-yellow new growth. But it is the
var. albertianas that have pushed new growth while the other forms
are still biding their time. 'Daisy's White' is fun now after
spending nine months of gray-green boredom. The diminutive 'Pixie
Dust' is spotted with opening buds, but it's the second flush later
in spring that will show off in yellow. 'Alberta Blue' is covered
with a hint of light blue in mid-April, but by summer we'll be
reminded that all blue Alberta cultivars can revert to portions of
green – at least all have at Buchholz Nursery.

When I worked for a
large container nursery in the 1970's they were known for growing
many hundreds of thousands of Albertas, indeed acres and acres. It
was my job to turn on the irrigation in the middle of the night to
stir up the air to keep the spruces from freezing…and it worked. I
guess I was a better employee then than an owner now,
or at least then I had more energy, because now I don't water at
night. Well, except for my middle-of-the-night trip into the
bathroom.

Another problem with
frost is the action we must take with our irrigation systems. At 31
degrees no pipes will break, but at 28-29 degrees some will. To
prevent damage, we drain the system and open valves, a task that
takes a good man about two hours. Then it's another two hours –
maybe the following day – to reactivate the system should we need
to water. The off-on undertaking costs close to $100, but then
repairing pipes is even more expensive. Of course, the weather
forecasts are just are just an approximation of what might occur, but
every day of the year I'm tuned into them.

Earlier I fretted
that the temperature was predicted to be 34 F (in Portland) with
frost in outlying areas. My whole life has been lived in an outlying
area. We closed all the greenhouse doors but we didn't drain the
irrigation. It was a balmy 36F when I got to work the next morning
and I was most pleased, so it appears my fret* was unfounded.

*Fret is from Old
English fretan, meaning “to devour.” You could say that fretting
is something that “eats away at us.”